Forward Sling Mount – Rem® 870 & Mossberg® 500/590
Nordic Components Shotgun QD Mount For Barrel Clamps [FC-816696021393] - Cheaper Than Dirt
Amazon.com: Gotical-Shotgun Mag Clamp with Sling Swivel 12 Gauge 1" Pack of 2 Shotgun Clamp New 1 Inch Shotgun Clamp Glass-Nylon Composite Used to Attach a Sling-Swivel to Some Shotguns (Black, 2Pcs)